Evaluation of autologous tissue sources for the isolation of endothelial cells and adipose tissue-derived mesenchymal stem cells to pre-vascularize tissue-engineered vascular grafts

Abstract

Currently used synthetic vascular grafts bear a high infection risk due to insufficient microvascularization of the graft wall disabling the infiltration of immune cells. Tissue-engineered grafts with a functional pre-vascularization thus would be desirable. However, autologous tissue sources for capillary forming cells need to be evaluated. Here, peripheral blood outgrowth endothelial cells (PB-OEC) from 17 healthy donors and pericyte-like mesenchymal stem cells derived from adipose tissue (ASC) of 17 patients scheduled for visceral surgery were characterized and investigated regarding their ability to form capillary-like networks in plasma-derived fibrin gels. To obtain proliferating PB-OEC with endothelial cell-specific properties (CD31-, VE-cadherin-expression, ac-LDL uptake and three-dimensional (3D)-tube formation in fibrin gels) both enrichment of CD34+ blood cells and young donor age was necessary (7/17, age≤24 years). In contrast, all isolated ASC revealed the expression of surface antigens expressed on pericytes [human neural/glial antigen-2 (hNG2), platelet-derived growth factor receptor β (PDGF-Rβ)] and showed mesodermal differentiation capacity. Moreover, co-culture of PB-OEC and ASC in fibrin gels resulted in highly branched capillary-like networks with significantly increased tube length (2.9-fold, p<0.0001) and number of junctions (8-fold, p<0.0001). In conclusion, successful cell isolation from autologous tissues for pre-vascularization of vascular grafts has been demonstrated although certain limitations for autologous EC require further strategies to enable the use of allogeneic cells.